Gaseous tube bending machine



April 22,1941. D. F. SAWYER GASEQUS TUBE BENDING MACHINE Filed June 4,1938 l|..ll IIII I INVENTOR.

BY flaw/a5 iawy e Patented Apr. 22, 1941 UNITED STATES PATENT OFFICE 1Claim.

This invention relates to a device for bending glass tubes, moreparticularly for bending glass tubes of the type used in gaseous tubelighting. Gaseous tubes of the neon type are used as light sources forvarious general illumination purposes, such as tramc signals, indirectinterior and exterior illumination with reflectors, etc. The lattertypes of installations require the tube to be wrapped in a very closespiral of a shape to obtain a concentration of illumination at the focalpoint of the particular reflector upon which they are to be used.

Heretofore, these spirals have been formed by hand and it is difficult,even for an expert glass worker, to obtain a perfectly contoured coiland to obtain uniformity in the coils.

The principal object of this invention is to.

provide a simple and convenient device for forming coils of any desiredshape with a perfect In the following detailed description of theinvention reference is had to the accompanying drawinge which forms apart hereof. Like numerals refer to like parts in all views of the Idrawing and throughout the description.

In the drawing:

Fig. 1 is a side view of the improved tube bending device.

Fig. 2 is an end view "thereof taken on the line 2-2, Fig. 1.

Fig. 3 is a detail perspective view of a typical coil as formed by thetube bending device.

Fig. 4 is a detail view of an alternate form of mandrel for use with thedevice.

The improved tube bending device comprises a vertical standard ll havinga bifurcated upper extremity ll, through the legs of which. two alignedpivot screws II are threaded. The poims of these screws rest inreceiving depressions in the opposite sides of a nut member II. Athreaded shaft II is threaded through the nut member 13 and terminatesat one extremity in a hand crank I! or other rotation imparting device.

At the other extremity, the shaft II is threaded, as shown at IE toreceive an attachment collar ll of a forming mandrel IS. The mandrel i8is formed with a contour to correspond with the desired contour of thecoil to be formed. It may be a conical mandrel of any desired inclineormay be a cylindrical mandrel as illustrated at I! in Fig. 4.

The mandrel is formed with a continuous, spirally-extending,coil-receiving groove 20. The shaft I4 is formed with a spiralthread-groove II. The pitch of the thread groove 2| corresponds with thepitch of the receiving groove 20.

The standard Ill supports the mandrel over any suitable heating burner22 preferably of a type to produce the usual ribbon burner flame.

In use, the crank is rotated to bring the first turn of the groove 20over the burner 22 and the heated glass tube is started around the firstturn of the groove 20. It is preferred in a conical coil, to start thefirst turn at the small end of the mandrel which acts to lock the coilto the end of the mandrel since it can not climb up the incline thereof.

The mandrel is then rotated and inclined to maintain the tube over theheating flame and wrap it into the groove 20. Since the thread groovesII are of the same pitch as the grooves 20, the forming portion of ofthe coil will be maintained over the burner 22 during the entireoperation.

The operator can tilt the shaft ii to position the mandrel and tube atthe proper height above the burner at all times during the windingoperation. This tilting action, of the shaft I I is very important uponconical coils, especially upon coils that are wound almost fiat.

' By tightening the screws 12 suflicient friction may be placed upon thenut to support the mandrel and tube until manually adjusted.-

While a specific form of the improvementhas been described andillustrated herein, it is desired to be understood that the same may. bevaried, within the scope of the appended claim,

without departing from the spirit of the invenbifurcated upperextremity; Divot bolts extending oppositely inward into the furcation ofsaid extremity: a nut member pivotally mounted between said bolts, saidnut member having a threaded passage extending therethrough at rightangles to said bolts; a threaded shaft threaded ceiving groove in thesurface of said mandrel, the

spiral of said groove corresponding in pitch to through said passage soas to project from both 5 the pitch of the threads on said shaft.

sides thereof and supported solely by said nut; a. crank'on oneextremity of said shaft; a ta- DAVID F. SAWYER.

